LVDS Comparator and Multiplexer Circuit for Single-Pair Full-Duplex Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low Voltage Differential Signaling (LVDS) interfaces require double the number of connections between sending and receiving circuits for simultaneous communication, limiting communication bandwidth and increasing interconnect complexity.
Innovation Solution
Design of LVDS drivers and receivers that enable simultaneous communication over a single pair of signal paths using a network of resistances and specialized input circuits, including inverters, differential receivers, window comparators, and multiplexers, to maintain appropriate signaling voltages and noise margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LVDS signaling is used for simultaneous bidirectional communication, then communication reliability is improved, but the number of connections required doubles
Solution Approach 1:
The patent merges bidirectional communication functionality into a single LVDS signal pair by combining transmitter and receiver circuits in both devices. Each device can simultaneously transmit and receive data over the same differential signal paths, eliminating the need for separate dedicated transmit and receive pairs while maintaining full-duplex communication capability
Solution Approach 2:
The LVDS signal pair is designed to serve multiple functions simultaneously - it can carry data in both directions at the same time, and the same signal paths can be used for different communication modes. The input circuitry is configured to accept signals from the LVDS pair regardless of which device is transmitting, making the connection universal for bidirectional data exchange
2Device complexity
If a single pair of signal paths is used for simultaneous bidirectional communication, then interconnect complexity is reduced, but voltage conflicts and noise immunity may worsen
Solution Approach 1:
The patent employs dynamic voltage control through resistive networks that automatically adjust voltage levels based on the communication state. When one device transmits, the resistive divider circuitry in the other device dynamically adjusts to maintain proper voltage levels, preventing conflicts when both devices attempt to drive the line simultaneously
Solution Approach 2:
Resistive networks are introduced as intermediary elements between the LVDS signal pair and the input circuits. These resistors act as mediators that buffer voltage conflicts, isolate noise, and maintain proper voltage levels without requiring complex active control circuitry
3Object-affected harmful factors
If LVDS signaling is implemented with double connections, then noise immunity is improved, but bandwidth and communication efficiency are limited
Solution Approach 1:
The patent enables continuous full-duplex communication where data transmission occurs simultaneously in both directions without requiring time-division multiplexing or connection switching. The LVDS signal paths continuously carry useful information bidirectionally, maximizing bandwidth utilization and eliminating idle periods that would reduce effective communication productivity
Data Source
AI summary
First and second devices may simultaneously communicate bidirectionally with each other using only a single pair of LVDS signal paths. Each device includes an input circuit and a differential output driver connected to the single pair of LVDS signal paths. An input to the input circuit is also connected to the input of the driver. The input circuit may also receive an offset voltage. In response to its inputs, the input circuit in each device can use comparators, gates and a multiplexer to determine the logic state being transmitted over the pair of LVDS signal paths from the other device. This advantageously reduces the number of required interconnects between the first and second devices by one half.